Fluid operated systems



Aug. 13, 1957 H. E. SHEETS ,4 FLUID OPERATED SYSTEMS Origina'i FiledJuly so, 1945 v 189 Fig.1? 190 65 186 & 177 157 I76 I66 179 I 185 191I56 i1 1/55 q] 192 i w I 167 I 193 n I 169 187 m zaf zas Z96 194 170 I195 175 l 171 181 7 mm United States Patent FLUID OPERATED SYSTEMSHerman E. Sheets, Akron, Ohio Substituted for abandoned applicationSerial No. 607,823,

July 30, 1945. This application August 12, 1952, Serial No. 303,957

13 Claims. c1. 137-625.4)

My invention relates to an improvement in fluid operated systems whichmay be used for providing a pneumatic or hydraulic control system or thelike.

Fluid motors have been constructed which comprise a cylinder having aslidable piston therein and means for introducing fluid into at leastone end of the cylinder for moving the piston. Movement of the piston inthe opposite direction may be eflected either by spring means or by areverse application of fluid in the opposite end of the cylinder.

It is the object of the present invention to increase the effectivenessand the efliciency of such fluid motors by incorporating an ejector orequivalent device in the fluid line leading to the fluid motor. It willbe evident that the incorporation of such an ejector device will resultin new and novel features in the operation of such fluid motors whichwere heretofore considered impossible.

I have found that by incorporating an ejector in the fluid line leadingto the cylinder and by providing a valve in series with the ejector, thefluid motor may be rendered much more efiective. The valve mechanism isso arranged that when the piston is to move in one direction fluidpressure will be introduced through the ejector into the cylinder. Insuch an operation the ejector is of no utility as it does not operate asan ejector during the flow of fluid through the ejector into thecylinder. When it is desired to move the piston in the oppositedirection the valve means are actuated to open the flow of fluid throughthe ejector to the exhaust. through the ejector creates a partial vacuumor low pressure in the suction room of the ejector, tending to reducebelow normal the pressure in the cylinder. As a result the end of thecylinder to which the ejector is connected may be quickly evacuated andreduced to a pressure below normal. The evacuation of the cylinder endmay actuate the piston in a reverse direction. This reverse movement mayif desired be supplemented by spring means or by fluid pressure on theopposite side of the piston.

In double acting fluid motor systems, a similar arrangement can be made.In such an instance, an ejector is connected to each end of thecylinder, and a fluid line through the ejector extends from a source offluid supply to the exhaust. Valve means are provided in each fluidsystem to permit fluid to flow through the ejector to create a partialvacuum in the suction room thereof, or to permit fluid under pressure toflow into the adjacent end of the cylinder. Obviously when one side ofthe cylinder is subjected to partial vacuum and the other side of thecylinder is subjected to fluid pressure a considerable pressuredifferential is provided between the cylinder ends.

A feature of the present invention lies in the use of my fluid motor forproportioning the flow of fluid from two or more sources to a singleoutlet. For example, my fluid motor is extremely useful in proportioningthe flow of hot and cold water to a common outlet. A valve may beprovided in each fluid line and these valves may be thermostaticallycontrolled. When the temperature of the outlet liquid drops below apredetermined temperature, one of the valves may be momentarily actuatedto open the valve. The opening of either valve will create a partial Icevacuum in the cylinder endconnected to the fluid line containing thevalve, causing a movement of the piston toward that end of the cylinder.Such movement may be used to increase the amount of hot water and todecrease the amount of cold water passing into the outlet. Similarlyshould the temperature at the outlet raise above a predetermined amount,the opposite valve may be thermostatically operated to permit a flow offluid through the valve, thus creating a partial vacuum in the adjacentcylinder end providing a movement of the piston toward that end of thecylinder. This movement of the piston may serve to allow more cold waterto enter the valve and to reduce the supply of hot water entering thesame.

The foregoing description is merely an example of the manner in which myfluid motor may be used to control a proportioning valve. In place ofthe arrangement described, a single acting piston may be employed whichmay or may not be spring loaded in onedirection.

A feature of the present invention lies in thefact that the speed ofoperation of the fluid motor may be effectively controlled by suitablecontrolling means used in series with the ejector. The speed ofoperation of the fluid motor may be regulated by controlling the flow offluid into or from the fluid motor.

An additional feature of the present invention rests in the fact thatfluid motors may act as a proportioning means for maintaining fluid at aconstant predetermined ratio. The fluid is supplied to a fluid motorthrough two inlet conduits and leaves the fluid motor through a suitablemixed outlet conduit. The proportioning of each of the two inlet fluidsmay be regulated by pilot valves in series with ejector means, this typeof proportioning means being extremely sensitive and readilycontrollable.

This application is a substitute for abandoned application 607,823 filedJuly 30, 1945.

In the drawings forming a part of my specification:

Figure 1 is a cross sectional view through a typical proportioningdevice showing one form of construction thereof wherein the piston isdouble acting.

Figure 2 illustrates a double acting cylinder showing the manner inwhich the piston may be selectively operated, first in one direction andthen in the other.

Figure 3 shows a modified form of proportioning device in which theactuated cylinder is of the single acting type.

Figure 4 is a view similar to Figure 3 showing the use of a spring toaugment the action of the ejector.

In Figure 1 of the drawings I disclose a proportioning deviceconstruction designated in general by the letter A. This constructioncomprises a body 61 which includes an elongated cylinder 62 andsubstantially ring-shaped intake ports 63 and 64. An inlet pipe 65 isconnected to the intake port 63 while the pipe 66 is in communicationwith the intake port 64. Opposite of the intake ports 64 and 63 Iprovide an outlet port 67 in communication with the outlet pipe 69.

For convenience in the description, the proportioning device A will bedescribed as a mixing device for proportioning hot and cold water. Thisis only illustrative of one use of the device and it is obvious thatother liquids for other purposes can be similarly proportioned. In thepresent instance, however, it may be considered that the pipe 65 formsan inlet pipe for hot water, while the pipe 66 forms an inlet pipe forcold water. The mixture of hot and cold water is discharged through thepipe 69.

An elongated hollow piston 70 is slidably located between the ends ofthe cylinder 62. The piston 70 includes spaced ends 71 and 72 which areof proper diameter to fit snugly within the cylinder 62. The centralportion of the piston 70 between the ends 71 and 72 may preferably bereduced in diameter as indicated at 73, and a partition wall 74separates the ends of the piston.

The end 71 of the piston 70 is of sufiicient length to entirely coverthe intake port 63 when the piston 70 is in the right hand positionillustrated in the drawings, the reduced diameter portion 73 acting toconnect the intake port 64 With the outlet port 67. In the oppositeextreme position of the piston '70 the end 72 of the piston is ofsufficient length to entirely close the inlet port 64, the reducing.diameter portion 73 of the piston forming the connection between theintake port 63 and the outlet port 67. At intermediate positions of thepiston 70 the intake ports 63 and 64 may be more or less opened. Whenthe piston is at the right hand position illustrated in the drawings theport 64 will be opened and the port 63 is closed. When the piston 70 isin center position, both ports 63 and 64 will be approximately half wayopen. As the piston 70 moves further to the left the opening to the port63 will increase, simultaneously decreasing the opening to the port 64.Thus the liquid entering through the pipes 65 and 66 may be properlymixed and allowed to leave the valve body through the outlet pipe 69.

In order to move the piston 70 I provide a fluid supply pipe which isconnected to a suitable source of fluid supply and which leads to the Tconnection 76. .One branch of the T 76 is connected by the pipe 77 tothe inlet end of the ejector 79, as will be later described. The otherbranch of the T is connected by the conduit 80 to the inlet end of theejector 81.

The ejector 79 includes a T-shaped body 82 having an inlet nipple 83threadably engaged in one end thereof. A clamping nut 84 holds the endof the pipe or conduit 77 to the nipple 83. An inlet nozzle 85 isengaged in the nipple 83 through which fiuid is directed from the inletpipe 75.

An outlet nipple 86 is threadably engaged in the outlet end of the body82 and an outlet nozzle 87 is engaged in the nipple 86; A nut 89 on thenipple 86 connects this nipple to a pipe 90 which leads to the controlvalve 91. The control valve 91 is connected to an outlet pipe 92 andacts to control the flow of fluid from the ejector 79. The suction room93 of the'ejector 79 is connected by the branch 94 of the ejector bodyto the end 95 of the cylinder 62.

The ejector 81 includes a nipple 96 secured in the inlet endthereof,vwhich is fastened by a clamping nut 97 to the pipe 80. An inletnozzle 99 is secured in the nipple 96 through which the incoming fluidmust flow.

A nipple 100 is engaged in the outlet end of the ejector 81 and anoutlet nozzle 101 is engaged in this t,

nipple. A clamping nut 102 secures the nipple 100 to the conduit 103which leads to a control valve 104 connected to a suitable dischargepipe 105. The suction room 106 of the ejector 81 is connected bythebranch 107 of the T-shaped body of the ejector to the end 109 of thecylinder 62.

In the operation of the system A, the fluid flows into the pipe 75 andis transmitted by the conduits 77 and 80 to the. ejectors 79 and 81. Ifthe valve 91 is closed the fluid under pressure will fill the suctionroom 93 and be transmitted through the branch 94 of the ejector body tothe left hand end of the cylinder 62.. The fluid pressure has a tendencyto move the piston 70 to the right or to maintain the piston in thisposition.

If the valve 91 is opened the fluid will pass from the pipe 77 throughthe inlet nozzle 85 and out through the outlet nozzle 87 of the ejector79, thus creating a reduced pressure in the suction room 93 which is incommunication with the left hand end of the cylinder 62. This reductionin pressure at this end of the cylinder has a I tendency to move thepiston 70 to the left from the position illustrated in Figure 1.

Similarly when the valve 104 is closed the fluid flows through the inletnozzle 99 filling the suction room 106 and passing through theconnection 107 to the right hand end of the cylinder 62, tending to urgethe piston 70 to the left from the position shown in Figure 1. Upon theopening of the valve 104 the fluid may flow directly from the inletnozzle 99 to the outlet nozzle 101, reducing the pressure in the suctionroom 106 and tending to evacuate fluid therefrom. This reduced pressurewill be communicated through the connection 107 to the right hand end ofthe cylinder 62, tending to move the piston 7 0 to the right or to holdthe piston in this position as shown in Figure 1. When both valves 91and 104 are closed the piston remains in any set position and will notmove. Thus it is possible to get a fixed and constant proportioningratio.

In the operation of the proportioning device the valves 91 and 104 maybe so operated by a control device, such as a thermostat, not shown-inthe drawings, that one valve closes as the other valve is opened. Thuswhen pressure tending to move the piston in one direction is exertedagainst one end of the cylinder the other end of the cylinder may beunder reduced pressure due to the other of the ejectors. Thus theejectors assist in the efiicient operation of the proportioning device.

In the system B, illustrated in Figure 2 of the drawings, I provide acylinder having a double acting piston 131 which is connected in anysuitable manner, as by nuts 128, to a piston rod 132. This rod 132passes through a packing joint 133 in the ends 134 and 153 of thecylinder 130 and may be used for any useful purpose. The fluid supply tothe cylinder enters through the intake pipe 135 which is connected to aT connection 136.

One branch of the T 136 is connected by the pipe 137' to theinlet end ofthe ejector device 139. The outlet end of the ejector device 139 isconnected by the pipe 140 to the valve port 141 of the three way valve142. The rotor or valve member 143 of the three way valve 142 isprovided'with a passage 144 therethrough which may provide acommunicating passage between the port 141 and the valve port 145 whichis connected to the outlet pipe 146.

The other branch of the T 136 is connected by a pipe 147 to the inletend of an ejector device 149. A pipe 150 connects the outlet of theejector device to the port 151 of the valve 142. When the passage 144through the valve member 143 is connecting the outlet pipe 140 to thepipe 146 the port 151 is closed by the valvev member 143. However, inanother. position the valve member 143 may connect the ports 145 and 151so that fluid may flow from the pipe 150 through the passage 144 in thevalve member 143 to the outlet pipe 146. In this case the valve member143 closes the port 141.

The suction room of the ejector device 139 is connected by the pipe 152to the cylinder 130 near the end 153 thereof. The pipe or connection 154connects the suction room of the ejector device 149 to the cylinder 130near the end 134 thereof. Either of the pipes 152 or 154 may transmitlow pressure or hi h pressure to the cylinder 130.

In the operation of the system B, fluid enters the inlet pipe 135 andflows through the T 136 and into the inlet of the ejector device 139. Asthe outlet of this ejector device is connected to the exhaust, fluidwill flowthrough the pipe 140, thepassage 144 and the outlet pipe 146. Areduced pressure is then experienced in the suction room of the ejectordevice 139, this reduced pressure being communicated to the left handend of the cylinder 130 through the pipe 152. A reduced pressure thenexists to the left of the piston 131, tending to draw this piston towardthe left into the position shown in the drawings.

T he fluid under pressure simultaneously passes through the pipe 147 tothe inlet of the ejector device 149. As the outlet 150 is closed by thevalve member 143 the fluid under pressure fills the suction room of theejector device 149 and is transmitted through the pipe 154 to the righthand end of the cylinder 130. Therefore a condition is reached whereinpressure is being reduced in. the left hand end of the cylinder 'due tothe action of the. ejector 139, while the full pressure of the fluid isbeing introduced into the other end of the cylinder 130. The piston 131will obviously be moved to the left into'the position shown in Figure 2.a H I i i If the valve member 143 is-turncd so that neither the pipe northe pipe is in communication with the outlet pipe 146, the inletpressure will be transmitted to both ends of the cylinder 130. Equalpressure will then be transmitted to both sides of the piston 131,holding the piston stationary. However, when the valve member is turnedso that the passage connects the port 151 to the outlet port 145, fluidmay then be forced from the inlet pipe 135 through the pipe 147, throughthe inlet and outlet of the ejector device 149, through the pipe 150,and through the valve member 143 to theoutlet pipe 146. This actioncauses a reduction in pressure in the suction room of the ejector device149 which is transmitted by the. pipe 154 to the right hand end of thecylinder1'30. Simultaneously, fluid pressure is applied to the left. endofthe cylinder due to the closing of the outlet of the ejector device139 by the valve member 143. Fluidfrom the inlet 135 istransmittedthrough the inlet of the ejector device 139 and the pipe 152 to the lefthand end of the cylinder 130. As a result the piston 131 is moved to theright.

In Figure 3 of the drawings II disclose a proportioning device which isoperated by a hydraulic system at one end only of the cylinder. Thesystem Cshown in Figure 3 includes a hydraulic cylinder 155 having apair of spaced inlets 157 and 156 thereto. A pair of pistons 1'59 and160 connected by a connecting rod 161 are slidable in the cylinder 155.A central outlet 162 is provided-inthe-cylinder 155 between the pistons159 and 160.

The piston 159 is spaced from the piston 160 so that when the piston 160is located at the end 163' of the cylinder 155 the piston 159 will closethe inlet 156. The piston 160 is arranged with respect to'the piston 158so that when this piston 159 is against the end 164 of the cylinder 155the inlet 157 will be closed bythe piston 160. The pistons 159 and 160are of such width as to entirely close the respective inlets while at anintermediate position of the pistons both of the inlets will be open acorresponding amount. As the double piston device moves to the rightfrom center position, the inlet 156 will close and the inlet157 willopen. As the double piston moves to the left from center position theinlet 156 will open and the inlet 157 will close. Thus any proportion offluids from the inlets may be mixed and may leave the cylinder 155through the outlet 162.-

In order to operate the pistons I provide a source of fluid supply whichis connected by a pipe 165:. to a regulat ing valve 166, which in turnis connected,- by a pipe 167 to the inlet of the ejector device 169.The. outlet of this device is connected by a pipe 170 to the regulatingvalve 171, which in turn is connected by the pipe. 172. to the valve173. This valve 173 is connected to a suitable outlet 174. The suctionroom of the ejector device 169 is connected by a pipe 175 to the end 163of, the cylinder 155.

In operation fluid enters through the inlet 165 to the ejector device169. If the valve 173 is closed the fluid pressure will be transmittedto the suction room of the ejector device and through the pipe 175 tothe right hand end of the cylinder 155 urging the. pistons to the left.However, when the valve 173 is opened and fluid pressure passes directlythrough the ejector device 169, creating a reduced pressure in thesuction room thereof, which is communicated through the pipe 175 to theright hand end of the piston 160 tending to move this piston to. theright as viewed in Figure 3. The speed of movement. of the pistons 159and 160 may be regulated by the regulating valves 166 and 171. Thepistons 159 and 160 may be held in any adjusted position by closing thevalve 166 and either the valve 171 or 173, when an incompressible fluid.is used. to operate this proportioning device. It may thus -is similarto the system C in most respects, but which includes the use of aspringfor urging the pistons in one direction. In this system I provide acylinder 177 having spaced inlets 179 and 180 thereto. A central outlet181 is provided through which the mixture of liquids may flow afterbeingmixed in the cylinder 180. A pair of pistons 182 and 183 are provided inthe cylinder 177 connected by a connecting rod 184. The piston 182 is sospaced fromthe piston 183 that when the piston 183 is located at the endwall 185 of the cylinder 177, the piston 182 will be in position toclose the inlet 179. Similarly when the piston 182 is located at thecylinder end Wall 186 the piston 183' will be closing the inlet 180. Aspring 187 is provided to urge the pistons 182 and 183 toward the end185 of the cylinder.

In'order to operate the pistons I provide a source of fluid supplyconnected by the pipe 189 to the control valve 190. This valve isconnected by a pipe 191 to the inlet of an ejector device 192, theoutlet of which is connected by a pipe 193 to a valve 194. The outlet ofthe valve 194 is connected to a suitable outlet pipe 195. The suctionroom of the ejector device 192 is connected by a pipe 196 to the end 185of the cylinder 177. A piston ring 197 is preferably provided on thepiston 183 to seal this piston with respect to the cylinder.

In the operation of the system D, fluid flows from the fluid supplythrough the valve to the inlet of the ejector device 192. If the valve194 is in closed position the fluid under pressure is transmittedthrough the pipe 196 to the right hand end of the cylinder 177, urgingthe piston 183 to the left and compressing the spring 187. This movementwill tend to open the inlet 179 and to close the inlet 180 to a more orless degree depending upon the extent of movement of the pistons. Whenthe valve 194 is open the fluid from the fluid supply can pass directlythrough the ejector 192 to the outlet pipe 195, thus causing a reducedpressure in the ejector device 192 which is transmitted through the pipe196 to the right hand end of the cylinder 177. This will cause movementof the pistons 182 and 183 to the right, acting to open the inlet 180and to close the inlet 179 to a greater or lesser degree.

The speed of operation of the pistons or other movable membersofthefluid motor in question within the various systems depends to someextent upon the pressure with which the fluid is supplied and the natureof the fluid used to operate the same. The operation is also materiallyaflected by the eificiency of the particular ejector used. If a quickmovement of the piston is desired a more efficient ejector should beused, or in some cases theviscosity of the operating fluid may belowered to render a given ejector more efficient. Obviously undersimilar pressure, size, and temperature conditions the fluid with a lowviscosity and within the range of high Reynolds numbers, such as a gas,will require only a relatively ineflicient ejector to produce thenecessary pressure dilference in the cylinder. Similarly a fluid with alower Reynolds number such as a liquid will require an ejector of higherefliciency. Various types of ejectors have been constructed, each ofwhich may be advantageous for a particular purpose.

Any suitable ejectors may be used in any of the systems described,depending upon the Work to be done, and upon the fluid to be used. It isnecessary to use an ejector suflicicntly effective and efficient toaccomplish the task with the particular fluid to be used and from thevarious ejectors may be selected one type which is sufiicientlyeflicient. p p

In accordance with the patent statutes, I have described the principlesof construction and operation of my improved fluid operated systems, andwhile I have en- I deavoredto set forth the best embodiments, thereof, I

desire to have it understood that obvious changes may be made within thescope of the following claims Without departing from the spirit of myinvention.

I claim:

1. A fluid system including in combination a fluid supply source, acylinder, a piston in said cylinder, ejector means connected to each endof said cylinder to control the pressure on opposite sides of saidpiston, said ejector means being connected to said supply source, anoutlet passage connected to each ejector means, and valve means in eachsaid outlet passage in downstream series with said ejectors controllingthe flow of fluid through said outlet passage connected to each of saidejector means.

2. A fluid system including in combination a fluid supply source, aproportioning device comprising a cylinder having a pair of'inletsthereto and an outlet therefrom, and a piston device operable in saidcylinder to proportion the flow of fluid from said inlets to saidoutlet, and means for operating said piston device including ejectormeans connected to each end of said cylinder to control the pressurewithin said cylinder at either end of said piston device, meansconnecting said ejector means to said fluid supply source, and valvemeans connected to the outlet of each ejector means controlling the flowof fluid through said ejector means, independent opening of each valvemeans actuating said piston device in one direction.

3. A fluid system including in combination a fluid supply source, aproportioning device comprising a cylinder having a pair of inletsthereto and an outlet therefrom, and a piston device operable in saidcylinder to more or less open either inlet while simultaneously closingthe other inlet, and means for operating said piston device comprisingejector means connected to each end of said cylinder to control thepressure on either end of said piston device, and valve means connectedto the outlet of each eject-or means controlling the flow of fluidthrough said ejector means, independent operation of each valve meanscausing a flow of fluid through its ejector actuating said piston devicein one direction.

4. A fluid system including in combination a fluid supply source, aproportioning device comprising a cylinder having a pair of inletsthereto and an outlet therefrom, and a piston device operable in saidcylinder to proportion the flow of fluid from said inlets to saidoutlet, and means for operating said piston device including ejectormeans connected to one end of said cylinder to control the pressurewithin said cylinder at the corresponding end of said piston device,means connecting said ejector means to said fluid supply source, andvalve means connected to the outlet of said ejector means in seriestherewith controlling the flow of fluid through said ejector means,opening of said valve means actuating said piston device in onedirection.

5. An independent fluid pilot system for controlling and proportioningseparate and independent liquid flows through a plurality of mixer valvepassageways including in combination a fluid supply source, a cylinder,a reciprocal piston variably adjustable to stationary intermediateposition between its limits of reciprocation in said cylinder whenoperated upon by fluid flow from said independent fluid source inindependent relationship to the liquid flowing through the mixer valvepassageways, ejector means in said independent fluid pilot systemconnected to one end of said cylinder to control variations of pressureon opposite sides of said piston, said ejector means being connected bya conduit means to said independent supply source, an outlet passageconnected to the ejector means in said independent fluid system, andadjustable valve means in said outlet passage in series with saidejector means for regulating and controlling the flow of fluid from saidsupply source through said outlet passage connected to said ejectormeans exclusive of the liquid passing through said mixer valvepassageways.

*valve'means in said outlet passage in series with said ejector meansfor'regu lating and controlling the flow of fluid from said separatesupply source through said outlet passage connected'to said ejectormeans.

7. A fluid control, system including in combination a cylinder,a'reciprocable variably adjustable piston movable within the cylinder,an associated element controlled by saidpiston, a separate fluid supplysource in independent relationship to the element controlled by saidpiston, ejector-means including .an inlet nozzle,.an outlet nozzle andan intermediate take-off nipple having communication withthe adjacentends of said nozzles and one end of said cylinder, a fluid supplyconduit connected to said :inlet nozzlefrom said separate fluid supplysource, a fluid outlet conduit connected to said outlet nozzle inindependent relationship to the element controlled by said piston, andan adjustable. valve connected to said outlet nozzlein seriesrelationship therewith for controlling continuous flow of, fluid fromsaid fluid supply source through said ejector means to vary and stop thesaidap'iston atjselective points intermediate the limits of itsreciprocal motion 8. The structuredescribed in claim 5 and including asecond ejector means connected to the other end of the cylinder, saidsecond ejector means including an inlet and an-outlet said inlet thereofbeing connected to said supply'source and .said outlet thereof having avalve connected thereto to control the flow through said second ejectormeansifrom said fluid supply source.

9. The structure described in claim 7 and including a second ejectormeans connected to the other end of the cylinder, said second ejectormeans including an inlet and an outlet, said inlet thereof beingconnected to said supply source, and said outlet thereof having a valveconnected thereto to control the flow through said second ejector meansfrom said fluid supply source.

10. The structure of claim 5 and including a means engageable with saidpiston normally biasing the same toward said one end of said cylinder.

11. The structure of claim 7 and including a means engageable with saidpiston normally biasing the same toward said one end of said cylinder. I

12. The structure of claim 5 and including a second valve in saidconduit between said ejector and said fluid supply source.

13. The structure of claim 7 and including a second valve in saidconduit between said ejector and said fluid supply source. 7

References Cited the file of this patent UNITED STATES PATENTS 962,111'Assmann June 21, 1910 2,009,102 Bern July 23, 1935 2,074,882 WunschMar. 23, 1937 2,099,563 "Henning Nov. 16, 1937 2,313,822 Hapgood Mar.16, 1943 2,354,791 Boldt Aug. 1, 1944 V Y FOREIGN PATENTS 381,757Germany Sept. 24, 1923

